A Licer bath for the pre-treatment of light metals is known from German Patent 3,246,323, column 2, lines 43-45. The word "Licer" originates from electroplating technical language; namely, the French "liser" meaning "to smooth, to polish." The bath is used in the German patent for the pre-treatment of articles of aluminum and aluminum alloys, before directly electroplating with nickel. Nickel layers are also deposited in the case of the present invention with the values given in the German patent (see column 3, paragraph 1), nickel anodes being used as the anodes.
In electroplating the possibility exists per se of immersing articles suspended on frames into the bath, or putting the articles into bulk materials containers such as vibrators or drums, then lowering the latter into the bath and then treating the materials. During this process at least the casing of the drum is rotated and the bulk materials then tumble and fall over one another, the operations making place statistically. In another process, the materials are vibrated with and in a basket, and the parts then tumble over one another statistically.
The drum is used with considerable reservations, because a statistical process is involved in which the geometry of the electrical fields and the inflow and outflow behavior of the liquids, etc., are understood only statistically. For example, there arise in the pre-treatment bath only statistically distributed point contacts when the bulk materials tumble and fall over one another. The same holds true for the vibration process.
Apart from metal deposition by electroplating with an externally supplied current, there is also electroless (chemical) metal deposition without external current. Although the desired aim of both technologies is the same, namely to deposit metal, the technologies are very different. Baths for the chemical deposition of nickel, copper, gold and the like are produced by Schlotter, Biasberg, M+T, and other companies.